Competition of As and other Group 15 elements for surface binding sites of an extremophilic Acidomyces acidophilus isolated from a historical tin mining site.

An arsenic-resistant fungal strain, designated WKC-1, was isolated from a waste roaster pile in a historical tin mine in Cornwall, UK and successfully identified to be Acidomyces acidophilus using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS) proteomic-based biotyping approach. WKC-1 showed considerable resistance to As and Sb where the minimal inhibitory concentration (MIC) were 22500 and 100 mg L, respectively, on Czapex-Dox Agar (CDA) medium; it was substantially more resistant to As than the reference strains CBS 335.97 and CCF 4251. In a modified CDA medium containing 0.02 mg L phosphate, WKC-1 was able to remove 70.30% of As (100 mg L). Sorption experiment showed that the maximum capacity of As uptake was 170.82 mg g dry biomass as predicted by the Langmuir model. The presence of Sb reduced the As uptake by nearly 40%. Based on the Fourier-transform infrared spectroscopy (FT-IR) analysis, we propose that Sb is competing with As for these sorption sites: OH, NH, CH, SO and PO on the fungal cell surface. To our knowledge, this is the first report on the impact of other Group 15 elements on the biosorption of As in Acidomyces acidophilus.